How many types of cyanobacteria

Cyanobacteria is a phylum comprised of photosynthetic bacteria that live in aquatic habitats and moist soils. Others are considered as an endosymbiont, serving as an endosymbiotic plastids in many eukaryotic cells. Cyanobacteria are found to play a role in producing gaseous oxygen as a byproduct of photosynthesis.

They are also believed to be associated with the Great Oxygenation Event. Some of them are nitrogen-fixers. Some live singly or in colonies, forming filaments or spheres. In the five-kingdom scheme of classification, Cyanobacteria used to be called Cyanophyta and is one of the phyla of the Kingdom Protista. They do not have true roots, stems, and leaves as embryophytes do. Recent studies and findings, though, caused changes in the taxonomic positions and led to newer systems of classification.

That is because this clade is comprised of species that are prokaryotic. In phycology , the blue-green algae are the only prokaryotic algae; the rest are eukaryotes. Thus, they are now classified as bacteria belonging to Phylum Cyanobacteria.

Cyanobacteria are characterized by the presence of pigments particularly phycobiliproteins that account to their blue-greenish colour. The phycobiliproteins are components of the phycobilisomes light-harvesting antennae for cyanobacterial photosystems. Phycobilisomes are embedded on the intracytoplasmic membranes thylakoids. These pigments are responsible for the blue-green pigmentation of cyanobacteria and they enable them to synthesize their own sugar through photosynthesis.

Some cyanobacteria e. Prochlorothrix , Prochlorococcus , Prochloron lack phycobilisomes and they have chlorophyll b instead. Cyanobacteria are prokaryotic.

They lack a membrane-bound nucleus. Nevertheless, they have microcompartments. For instance, carboxysome is a compartmentalized cage-like structure surrounded by a protein shell.

Apart from photosynthesis, the thylakoids are also involved in cellular respiration. While the thylakoid machinery for electron transport is used for photosynthesis in the light during the day it is then used for respiration in the dark at night. Filamentous species may differentiate into vegetative cells photosynthetic cells , akinetes spores resistant to harsh environmental conditions , or to heterocysts cells capable of nitrogen fixation by producing the enzyme nitrogenase.

Apart from photosynthesis, cyanobacteria are capable of nitrogen fixation through heterocysts. Quantifying the components of underestimation. Glob Ecol Biogeogr — Article Google Scholar. Curr Biol — Trends Ecol Evol — PubMed Article Google Scholar. J Biosci — Biodivers Conserv — Proc R Soc B — Divers Distrib — Box GEP Some problems of statistics and everyday life.

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Worldwide, these blooms are increasing in magnitude, frequency, and in geographical spread. With warmer temperatures associated with climate change, cyanobacteria are blooming in more northern latitudes.

Stormwater associated with climate change induced high intensity rainfall, carries nitrogen and phosphorus into surface waterways. Because cyanobacteria also grow well in still water, blooms are becoming more frequent in rivers that have been dammed to create reservoirs. With a rapidly changing climate, warmer weather, more intense rainfall, and pollution caused by human activity, we are perpetuating optimal conditions for harmful algal blooms. In high densities, these algae may discolor the water and outcompete other life forms.

There are numerous health and ecological effects associated with toxic cyanobacteria blooms. Humans are at risk to exposure while recreating in affected waters through ingestion, skin contact, and when airborne droplets containing the toxins are inhaled while swimming.

Humans are also exposed to cyanobacteria when consuming shellfish from water bodies containing a high concentration of cyanotoxins. Although humans are at risk of exposure, it is very hard for officials to track cases of human illness caused by harmful algal blooms because minor symptoms are overlooked.

The effect of cyanobacteria on human health varies with the type of toxin present, its concentration, and the duration of exposure. The higher the concentration of cyanotoxin and the longer the exposure, the more severe the symptoms may be. Health effects usually occur when exposed to a high concentration, but some people may be more susceptible to developing symptoms.

Skin contact with cyanotoxins can cause irritation of the skin rash or skin blisters , eyes, nose and throat, and inflammation of the respiratory tract.

Swallowing water containing high concentrations can lead to nausea, vomiting, abdominal pain and diarrhea. Effects on the liver and nervous system of animals and people have also been documented in severe cases. Dogs, livestock and other animals that drink water from affected areas or lick their fur to clean it are at a much higher risk of toxins than humans.

Animals usually drink from areas on the edges of affected water, where algae tend to accumulate. Livestock and pet deaths have occurred after these animals have consumed large amounts of toxic algal scum accumulated along shorelines. There is increasing interest in considering the "One Health Approach" when addressing cyanobacteria effects.